Method for finishing denim

ABSTRACT

A method for denim finishing, with desizing, bleaching, and/or dyeing of the goods is described. In order to move the desizing and/or bleaching into a treatment line through which the web of fabric passes continuously, ahead of the production of the clothing, the goods are treated in the moist, hot ambient air of a hot flue.

[0001] The invention relates to a method for denim finishing, proceeding from goods to which a treatment agent, such as a desizing agent, a bleach, or a dye, is applied, whereby the treatment agent is activated on the goods in a hot flue, by means of drying with moist, heated circulating hot flue air.

[0002] The denim process chain in the production of denim clothing, e.g. so-called jeans, comprises essentially three stages, proceeding from the woven fabric: denim finishing, production of the clothing, and finished piece finishing. Denim finishing, also called fabric finishing, generally includes dyeing, washing and/or drying, as well as frequently, making the woven fabric shrink-resistant. Hot flues are often used in treatment lines of fabric finishing, to dry the goods (with continuous through-put). In the production of the clothing, the clothing pieces are cut and sewn. The finished clothing articles are subsequently treated in the finished piece finishing system, piece by piece, for example desized, stone-washed and/or bleached. Bleaching normally takes place only on the finished article of clothing, because in this way, the seam regions can be bleached more than the rest of the fabric. The same holds true for stone-wash treatment. The wet treatment of the finished pieces, in each instance, is followed by a drying stage, e.g. having a tumbler. In the finished piece treatment, the individual process stages or machines, which cannot be coupled for continuous goods transport, follow one another discontinuously.

[0003] The sizing that is still present on the finished woven fabric can also be removed before the clothing production takes place; for this purpose, separate steamers through which the goods run continuously are generally used in practice. After the steaming process, the goods generally have to be dried.

[0004] A hot flue is described in DE 33 36 328 C2. The known hot flue comprises an upper series and a lower series of guide rollers that are mounted parallel to one another and horizontally in a hot flue housing. The housing possesses a horizontal slit in an inlet wall, through which the goods to be treated (web of fabric) are to be introduced, spread out. The goods are transported alternatively over an upper guide roller and a lower guide roller, in loop or meander shape. Within the housing, rows of blowing nozzles arranged parallel to the guide rollers are provided, which are used to blow a heated treatment agent, particularly air, usually ambient air, onto the goods and into the spread-out loops of the web of fabric. Hot flues can be easily integrated into treatment lines through which a web of fabric passes continuously, and serve as drying stages there.

[0005] The invention is based on the task of taking over the treatment stages necessary for individual piece, i.e. finished piece finishing, to the extent that this is technologically possible, in the woven fabric finishing (denim finishing), and in a treatment line there through which the web of fabric passes continuously. In addition to the dyeing that has already been taking place here, desizing and a significant part of the bleaching are supposed to be carried out in the fabric finishing. As compact as possible a mode of operation is aimed at, in which the treatment procedures, i.e. means, are performed in a single pass, preferably in one and the same work step. The invention is particularly based on the task of creating a method for desizing a woven fabric, particularly a denim, which can be integrated into a continuous treatment line, with the goods being continuously passed on from one treatment stage to another treatment stage, but which does not require a separate desizing steamer. Preferably, the invention is also or simultaneously based on the task of transferring the time-consuming, discontinuous bleaching process from the finished piece finishing stage to the fabric finishing (denim finishing) stage, to the extent that the goods are to be bleached essentially uniformly (uni). It would also be desirable, according to another task, to combine desizing and/or bleaching with dyeing.

[0006] The solution according to the invention is characterized, for the method for denim finishing indicated initially, proceeding from goods to which a treatment agent is applied, by integration into the continuous course of the web of fabric, which begins after weaving (with the unfinished woven fabric) and ends, without interruption, only before production of the clothing, with the finished web of fabric.

[0007] The treatment agent, in each instance, is activated in a hot flue, by means of drying, using moist and heated hot flue ambient air on the goods, particularly in the sense of desizing, bleaching, or color fixing. By means of the heated and, at the same time, moistened hot flue ambient air, the so-called cooling limit temperature (see Dubbel, Taschenbuch für den Maschinenbau [Pocketbook for Machine Design], Springer-Verlag, 1974, page 465) of the treated goods is increased. The increased goods temperature, in turn, results in an acceleration of the (chemical) reactions that take place during bleaching, desizing, dyeing (color fixing), or the like. Surprisingly, it is possible that a web of fabric to which the treatment agent, in each instance, or several treatment agents, has/have been applied, can be finished in a single pass, when using the invention. The treatment stages that normally follow dyeing, bleaching, or desizing, such as washing and drying, can follow this finishing in a hot flue.

[0008] Accordingly, a significant part of the bleaching that is desired in the case of denims, i.e. jeans, can be moved into the fabric finishing that is performed continuously on the web of fabric. In this way, at least the duration of the bleaching stage in the course of the finished-piece treatment is reduced. Furthermore: desizing itself requires neither steaming of the web of fabric before production of the clothing nor washing of the finished pieces after production. In this way, the duration of the washing process required in the finished-piece finishing, e.g. for bleaching, is also reduced. Surprisingly, during desizing, a separate steamer can be completely eliminated, because the moistened, hot ambient air of the hot flue can be used for activating the sizing, just like in a steamer, while it performs its actual task.

[0009] The treatment agents, for example for bleaching, desizing and/or dyeing, can be applied to the web of fabric in conventional manner, for example by means of foularding and subsequent removal by squeezing, as well as pre-drying, within the scope of the method according to the invention. The treatment in a hot flue is then followed by this, continuously. If the bleach, in each instance, cannot be applied at the same time as a dye, which is frequently the case, it is at least possible, within the scope of the invention, to perform the bleaching and the desizing, or the dyeing and the desizing, in a single pass, in other words in one pass through a hot flue or a sequence of hot flues, with the web of fabric being moved continuously from one treatment unit to another treatment unit. Hydrogen peroxide can be used as a bleach, for example.

[0010] According to the invention, the entire denim finishing process is integrated into a continuous progression of the web of fabric, which begins after the weaving, with the unfinished woven fabric, and ends, without interruption, only just before production of the clothing, with the finished web of fabric, e.g. after shrinking. The unfinished goods (denim) are presented to this continuous treatment. The goods are first gassed, among other things, then desizing agent, dye and/or bleach is applied to them, then they are washed, pre-dried mechanically and/or thermally, biased and, if the fabric in question is non-elastic, particularly non-woof-elastic denim goods, immediately shrunk. Elastic denim goods are additionally supposed to be fixed in a drying/fixing system, before being shrunk.

[0011] Using the attached block schematic, an example of a progression of a web of fabric through a system for implementing the method according to the invention will be explained. After rolling, stripping, and gassing of the woven fabric in Stage 1, the goods W, continuously transported in the direction of the arrow, are washed, squeezed out, and foularded again in Stage 2, for example with desizing agent and bleach or dye. The treatment agents applied are activated in a hot flue 4. Non-elastic denim goods are stretched on a bias in Stage 5, and passed over a stentering frame 6 as well as a rubber and felt calander 7 to control their width. Elastic denim goods (particularly also woof-elastic goods) are generally additionally thermo-fixed in the stentering frame 6. After the fixing process, the over-dry goods are cooled, and shrunk in Stage 8, possibly after having been moistened again. A run-out combination 9 with a trough and a Sochor roller can assure low-tension roll-up of the shrunk non-elastic or elastic goods.

[0012] This method of procedure to be carried out continuously, from the unfinished fabric bale to the fabric finished and ready for production of clothing, in an uninterrupted pass, makes it possible to significantly lower the costs per length unit of the web of fabric produced, as compared with the conventional method of procedure using systems that work discontinuously (after clothing production). A significant advantage of the method of procedure according to the invention is that the desizing and the bleaching can also be integrated into the treatment line for continuous operation. According to the invention, the washing machines and tumblers conventionally required for the treatment of finished pieces are thereby eliminated, at least in part.

[0013] The advantages of the fully continuous method for the treatment of non-elastic or (woof)-elastic denim goods, according to the invention, are: greater utilization effect of the system, higher production speed, less space required, and lower personnel costs as compared with the case of the conventional method of procedure using discontinuous production lines. 

1. Method for denim finishing, proceeding from goods to which a treatment agent, such as a desizing agent, a bleach, or a dye, is applied, whereby the treatment agent is activated on the goods in a hot flue, by means of drying with moist, heated circulating hot flue air, characterized by integration into the continuous course of the web of fabric, which begins after weaving (with the unfinished woven fabric) and ends, without interruption, only before production of the clothing, with the finished web of fabric. 